IFS.py 文件源码

def sph_ifs_correct_spectral_xtalk(img):
    '''
    Corrects a IFS frame from the spectral crosstalk

    This routines corrects for the SPHERE/IFS spectral crosstalk at
    small scales and (optionally) at large scales. This correction is
    necessary to correct the signal that is "leaking" between
    lenslets. See Antichi et al. (2009ApJ...695.1042A) for a
    theoretical description of the IFS crosstalk. Some informations
    regarding its correction are provided in Vigan et al. (2015), but
    this procedure still lacks a rigorous description and performance
    analysis.

    Since the correction of the crosstalk involves a convolution by a
    kernel of size 41x41, the values at the edges of the frame depend
    on how you choose to apply the convolution. Current implementation
    is EDGE_TRUNCATE. In other parts of the image (i.e. far from the
    edges), the result is identical to original routine by Dino
    Mesa. Note that in the original routine, the convolution that was
    coded did not treat the edges in a clean way defined
    mathematically. The scipy.ndimage.convolve() function offers
    different possibilities for the edges that are all documented.

    Parameters
    ----------
    img : array_like
        Input IFS science frame

    Returns
    -------
    img_corr : array_like
        Science frame corrected from the spectral crosstalk

    '''

    # definition of the dimension of the matrix
    sepmax = 20
    dim    = sepmax*2+1
    bfac   = 0.727986/1.8

    # defines a matrix to be used around each pixel
    # (the value of the matrix is lower for greater
    # distances form the center.
    x, y = np.meshgrid(np.arange(dim)-sepmax, np.arange(dim)-sepmax)
    rdist  = np.sqrt(x**2 + y**2)
    kernel = 1 / (1+rdist**3 / bfac**3)
    kernel[(np.abs(x) <= 1) & (np.abs(y) <= 1)] = 0

    # convolution and subtraction
    conv = ndimage.convolve(img, kernel, mode='reflect')
    img_corr = img - conv

    return img_corr